The present invention relates to a device for feeding a wire into a stitching head of a duplicating machine or the like and in one of its aspects relates to a device for guiding, detecting, and straightening a wire before the wire is fed into a stitching head of a duplicating machine or the like wherein the device includes a deflecting head that is essentially self cleaning.
Wire feed devices are commonly used in certain equipment (e.g. duplicating, copier, and like machines) for guiding, detecting and straightening a stitching wire before the wire is supplied to a stitching device. The stitching device, in turn, forms the wire into staples or the like which, in turn, are then used to secure a stack of sheets (e.g. copies) together at the exit of the copier. For example, German patent application DE 197 52 285 A1 describes a stitching device of this type which form staples from wire is stored in a cartridge that is fastened to the stitching device.
Another such wire feed device is disclosed in German patent application DE 197 12 862 wherein the leading end of the wire is fed from a stitching wire supply spool into a sheet stack stitching device through a guide tube. The wire supply spool is mounted on a movable bracket, which allows the supply spool to be moved between inside the device and the outside thereof. The stitching wire is transported through a guide tube to a wire-cutting device, a staple-forming device, and a staple-driving device, all of a conventional type. A first wire sensor extends into the transport path of the stitching wire and signals the user when the leading end of the wire passes by. This signal indicates that the manually driven threading procedure has ended and the stitching wire is ready for further motor-driven transport. The stitching wire is then further advanced until the leading edge of the stitching wire triggers a second wire sensor in the transport path which, in turn, stops the advance of the wire when the leading end of the wire reaches its delivery position within the stitching device. In this device, the wire sensors are actuated when the wire, itself, completes a respective electrical circuit.
The unexamined, laid-open German patent application DE 31 20 813 A1 discloses the use of wire sensors, such as those mentioned above, for sensing the wire transport, in a nonstop wire feed device for stitching equipment. In this device, a separate wire, from its own supply spool, is transported to an individually designed wire supply nozzle. A particular stitching wire is drawn from its spool by means of guide and transport rollers and is transported to its supply nozzle with the use of swiveled guide rollers that are insulated from ground. The wire, as it is being advanced, closes an electrical circuit, which, in turn, controls the advance of the wire through its assigned wire supply nozzle. Sensors in the wire transport nozzles close another respective electrical circuit upon contact with the wire, which, in turn, causes an indicator lamp to light up and thus indicate which wire supply nozzle is currently supplying wire.
Prior wire feed devices of the type have experienced problems due to abrasion of the wire, which occurs as the wire is guided and straightened within the feed device. As the wire abrades under prolong use, unwanted residues (i.e. metal shavings or bits of wire) can build-up and accumulate inside of the stitching device. Since this accumulated residue can conduct electricity, it can short the electric circuit of a wire sensor and thus produce a false signal.
This abrasion is caused, in part, because the wire contacts feed inlet and guide bushings in the prior wire feed devices that are typically made of a hardened material, e.g. steel. Further, abrasion may result when the cross-sections (e.g. circular) of the transport passages in these feed devices do not correspond to the rectangular profile of the stitching wire thus allowing some play in the wire as it moves therethrough. The latter problem has been recognized, see U.S. Pat. No. 4,444,347 wherein the use of a rectangular wire feed guide in the straightening sleeve of a wire feed device is suggested. When the wire is also rectangular, abrasion and the resulting residue in the stitching device is reduced.
However, even when a rectangular wire is guided and straightened through a rectangular wire guide, there is a likelihood that some abrasion will occur. Over a period of time, the abraded material (e.g. shavings, wire bits, etc.) can accumulate within the wire feed device which which, in turn, will adversely affect the performance of the device. Accordingly, it will be necessary to regularly clean the wire feed to remove this residue. Since the wire supply is generally positioned within highly sophisticated equipment, the wire supply is typically not readily accessible thereby making the maintenance thereof difficult and cost-intensive.
Accordingly, it can be seen that any device that can feed a stitching wire reliably to a wire utilization device (i.e. a stitching head for producing stitching wire bindings (staples) in a duplicating machine) and that, at the same time, has a low sensitivity to any material abraded from the wire, is highly desirable.
According to one aspect of the present invention, a wire feed device is provided for guiding and straightening a continuous strand of wire from a source to a utilization means (e.g. stitching mechanism) within a duplicating machine or the like. According to one embodiment, the wire feed device is comprised of a wire infeed unit and a deflection head which are connected together by a flexible guide hose which provides a continuous guide path for the wire through the wire feed device.
According to one further aspect of the invention, the wire infeed unit is comprised of a housing having an opening therethrough, which is adapted to guide the wire therethrough. An inlet nozzle, preferably made of an electrical nonconductive material (e.g. ceramic) and having a first guide passage therethrough, is releasably connected to the housing at the inlet end of the opening and a feed bushing having a second guide passage therethrough is mounted at the outlet end of the opening. The entries into both the first and second guide passages are tapered and the cross-sections of the passages are preferable rectangular (e.g. square) to alleviate abrasion of the wire as it passes through the wire infeed unit.
A contact element (e.g. a hollow cylinder) may be spring mounted in the opening between the inlet nozzle and the feed bushing and is adapted to remain in continuous contact with the wire as the wire passes therethrough. The center axis of the first guide passage in the inlet nozzle and the center axis of the second passage in the feed bushing are offset from each other to aid in maintaining the wire in contact with the contact element as the wire is advanced therethrough. An electrical conductor extends from the contact element to outside the housing where it is adapted to be connected to an electrical circuit which, in turn, will be closed to generate a signal when the wire is in contact with the contact element.
The deflection head according to one further aspect of the invention is comprised of a housing, which is preferably made in at least two parts, (e.g. a base plate and a cover plate) due to the sophisticated geometry of the housing. Further, for the ease in manufacturing, micronized powder injection molding methods can be used advantageously, wherein both metal (metal injection molding, MIM) and ceramics (ceramic injection molding, CIM) can be processed. The process technology is based on sintering an injection-molded part (green compact) to a solid body that is largely free of pores. In order to process the powder using injection molding technology, it is mixed with an organic binding agent to attain a thermoplastic molding compound. The binding agent must be removed again before sintering, which is usually carried out by smelting or catalytic degradation (see R. Rupprecht: xe2x80x9cMold release methods for microstructured components of plastic and metal,xe2x80x9d 4th Status Colloquium PMT: Karlsruhe Research Center (2000)). Preferably, the deflection head is produced of metal using micronized powder injection molding or a comparable method wherein the deflection head will consist of two metal or ceramic parts that interlock with each other.
The housing of the deflection head may have a guide passage therethrough that is essentially arc-shaped whereby the wire is gradually deflected 90xc2x0 as it passes through the deflection head. Outwardly radiating pockets are provided on at least on one side of the guide passage. Because of these pockets, debris (e.g. the material abraded from the wire and wire shavings) are removed from the wire and are transported out of the inside of the wire feed device due to the feeding of the wire and/or vibrations. This results in a self-cleaning of the wire feed device. The apparatus may be oriented such that gravity assists in drawing the debris through the pockets and out of the feed-head.
Preferably, dimpled guide points are formed on the other side of the arc-shaped guide passage wherein the grooves between the dimpled guide points are effectively aligned with respective pockets. This facilitates the self-cleaning of the wire guiding device.
A wire straightening sleeve may be positioned downstream of the deflection head and is adapted to receive the wire as it exits the head. Straightening sleeve may have a sheath of an electrically insulating material, e.g. plastic, thereon. The wire straightening sleeve may have an electrical connector which extends through the sheathe to provide a connection to a control and/or monitoring circuit which is closed when the wire contacts the sleeve.
The present invention can be used in all stitching devices in which printed or unprinted print media are conjoined with one another. In addition, use is possible in all devices in which a wire in general is guided, detected and/or straightened and in which wire abrasion possibly poses a problem.